题目内容
Laying eggs the ant queen's full-time job.
|
A．is |
B．are |
C．has |
D．have |
A
【解析】略
Antarctic seabirds are breeding（繁殖）later, because thinner sea ice is causing their food supplies to decline, a new study says. The birds, which nest in East Antarctica, have delayed their spring arrival by an average of nine days and egg-laying by an average of two days over the past 50 years, according to polar researchers from the French National Center for Scientific Research in Villiers en Bois, France, study authors Christophe Barbrand and Henri Weimerskirch attribute this later breeding activity to decreases in sea ice caused by climate change. 根据短文内容，从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。
__1____Painkillers in a tablet can make your headache go away. Antibiotic cream（抗生膏）from a tube can prevent your cuts from becoming infected. But can medicine come packaged in chicken eggs?
A team of scientists from Scotland says yes. They've engineered special chickens that lay eggs with disease-treating drugs inside.
_2____Animals make thousands of proteins—they’re the main ingredient in skin, hair, milk, and meat. Since animals can make proteins easily, they’re good candidates for making protein drugs.
Researchers have already made cows, sheep, and goats that pump out protein drugs in their milk. But chickens are not expensive to take care of; what’s more, they need less room, and grow faster than these other animals. “ __3____”says Simon Lillico of the Roslin Institute near Edinburgh, Scotland.
Lillico and a team of researchers changed chickens’ DNA—the code that tells cells how to make proteins so that the birds’ cells made two protein drugs. __4____
The scientists altered the chickens’ DNA so that the birds made these drugs only in their egg whites (蛋清). This protects the chickens’ bodies from the drugs’ possible harmful effects and makes it easy for scientists to collect the drugs.
These special chickens can pass on their drug-laying abilities to their chicks. __5____ The scientists need to improve these chickens before they roost (栖息) in drug companies’ labs. The birds don’t make enough drugs to treat people yet. But once the researchers perfect their technique, you might eventually take your medicine sunny-side up.
| A．Medicine comes in lots of different uses. |
| B．Those qualities could make chickens a better choice to become living drug factories. |
| C．So far, the Scottish researchers have bred five generations of drug—producing birds. |
| D．Some chickens are found having the ability of treating diseases. |
F. These drugs are made of molecules called proteins.
G. Medicine comes in lots of different packages.